Users can upload most file types up to 25MB -- the same file size limit as Gmail. The exceptions: music files (sorry, old-school Napster fans) and executable (.exe) files (sorry, hackers). But e-books, comics, music videos and other small movies are fair game.
To prevent the spread of malicious, inappropriate or copyrighted files, "users can report files the same way they can with other content across the site," a Facebook spokesperson said. Whether a group that wants to share such things will willingly turn itself in remains to be seen.
Below is a snapshot of the file-sharing feature: